/Engine/Source/Runtime/Slate/Public/Framework/Application/SlateApplication.h
Called when a drag from an external (non-slate) source enters a window
true if the drag enter was handled and can be processed by some widget in this window; false otherwise
bool ProcessDragEnterEvent ( [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWindow](API\Runtime\SlateCore\Widgets\SWindow) > WindowEntered, const [FDragDropEvent](API\Runtime\SlateCore\Input\FDragDropEvent) & DragDropEvent )